In U.S. Pat. No. 4,693,704, a cervical canal catheter is described which is intended to treat premature rupture of the membrane before the beginning of parturition, efflux of amniotic fluid from the womb and the onset of parturition.
In that arrangement, a two lobe balloon seal is inserted into the cervical canal and the balloons are inflated or expanded so that one of the balloons seats primarily at the isthmus of the uterus while the other is located generally within the canal. Key to this system, in addition to the gourd-shape of the balloon which engages at the isthmus of the uterus, is the provision of or a requirement for a ligature which extends through the body of the cervix between these tubes to prevent the widening of the cervical canal and ejection of the stopper formed by this assembly.
The goal is to prevent amniotic fluid from efflux through the cervical canal.
The device also provides a tube which extends through the balloon and provides communication with the uterus or womb so that amniotic fluid can be withdrawn in premature rupture of the membranes.
In practice, the requirement for the ligature in the wall of the cervix in the region of the inserted plug between the two balloons has been found to be disadvantageous because the application of the ligature is an invasive procedure and may be a cause of preterm labor.
Without the ligature, the stopper may be ineffective.
Mention may also be made of U.S. Pat. No. 4,100,923 which provides a balloon which fits into the cervix and has a pair of resilient flanges, one of which forms a cup over the mouth of the cervix while the other lies across the cervical canal within the womb.
The balloon is inflated through one passage and a further passage extends through the balloon to administer medication to the extra amniotic space in an impregnated uterus, e.g. for abortion.
This arrangement also has been found to be disadvantageous as a plug for the cervix and depends, for its sealing effectiveness, upon the balloon practically completely filling the cervical canal and the distortion of the cervical canal upon introduction to allow the relatively large flange which seats against the inner end of the canal, to provide the seal.
Mention may also be made of U.S. Pat. No. 4,430,076 which provides a uterine manipulative and injection device which engages in the womb and expands against the isthmus of the cervical canal and operates with a fixedly positioned enlargement or stop surface. This device is complex to insert and also has not been found to be fully satisfactory.
Finally, reference may be had to the pressure positive catheter described in U.S. Pat. No. 2,936,760 which is intended for insertion into the urethra and to be able to close both ends of the urethra in conjunction with introduction of a medium into the urethra of a female patient, particularly in connection with positive pressure urethrography. In that system, as well, two expandable balloon elements are provided.